JP7567040B2 - Solvent-based two-component anticorrosive coating composition - Google Patents

Description

The present invention relates to a solvent-borne, two-pack coating composition comprising at least a pigmented and/or filled masterbatch component (A) comprising at least one polyhydroxyl-functional aromatic organic compound and at least one polymer and/or resin having functional groups reactive to at least one crosslinker contained in the hardener component (B); (B) a hardener component, and optionally (C) a solvent component. The present invention further relates to a method for producing the coating composition, a method for coating a metal substrate with the coating composition, the thus obtained coated substrates, in particular multi-layer coated substrates and their manufacture, and a method for using the polyhydroxyl-functional aromatic organic compound in the solvent-borne, two-pack coating composition to impart corrosion protection to the cured coating formed from the coating composition.

In many areas of painting of metal parts, for example in the field of car repainting, commercial vehicle painting, aircraft painting, and also in the case of large technical machine systems such as wind power systems, it is usually necessary to protect the respective metal parts used, in particular parts made of aluminum and/or aluminum alloys, against corrosion using a corrosion protection coating. The demands on corrosion protection are very high, especially since manufacturers often guarantee corrosion protection for many years.

However, the corrosion of aluminum is significantly different from that of iron-containing substrates. In particular, filiform corrosion is often observed in aluminum-based substrates, such as pure aluminum or aluminum alloys.

Anticorrosive pigments are often employed in coating compositions to protect metal substrates from corrosion, but the use of anticorrosive pigments often involves the use of environmentally problematic inorganic lead-based or chromate-based anticorrosive pigments, or particularly problematic organic corrosion inhibitors. Moreover, such pigments are typically used in large quantities, which can significantly alter the properties of the coating composition beyond their primary purpose of providing corrosion protection.

In particular, in two-component coating compositions, such as automotive refinish coating compositions, where highly reactive polymers, resins and/or crosslinkers are used, certain organic corrosion inhibitors are not considered to be effective because they are consumed by reaction with such polymers, resins and/or crosslinkers.

For example, Ulaeto et al. in their scientific paper entitled "Smart nanocontainer-based anticorrosive bio-coatings: Evaluation of quercetin for corrosion protection of aluminum alloys" (Progress in Organic Coatings 136 (2019) 105276) propose encapsulating quercetin in mesoporous silica nanocontainers and using the encapsulated quercetin in a room temperature curing, solvent-free, two-part coating composition. The idea is that encapsulation protects quercetin from reactive components of the coating composition, allowing the encapsulated quercetin to remain in the nanocontainers in the curing composition until corrosion phenomena caused by an increase in pH value to about 10 occur. Thus, the use of organic corrosion inhibitors in coating compositions without prior protective nanoencapsulation generally results in undesirable inactivation of such corrosion inhibitors during the curing process. However, although encapsulated organic corrosion inhibitors may not participate in crosslinking reactions, their corrosion protection action is limited to very high pH values to become effective. However, corrosion of metal substrates, such as aluminum-containing substrates, may be caused by other mechanisms in addition to the increase in pH required to release the organic corrosion inhibitor from the mesoporous silica nanocontainers. In particular, corrosion under acidic conditions or in acidic environments may occur when the release mechanism of the action of the encapsulated rust inhibitor is not effective.

Aluminium-based substrates in particular need to be protected from corrosion, but the coating material should also be suitable for adopting corrosion resistance on other metal substrates, such as different types of steel.

Ulaeto et al., “Smart nanocontainer-based anticorrosive bio-coatings: Evaluation of quercetin for corrosion protection of alumin um alloys” (Progress in Organic Coatings 136 (2019) 105276)

While known techniques often utilize the crosslinking-promoting properties of some anticorrosive pigments or certain organometallic or metal-containing catalysts, the object of the present invention was to achieve excellent anticorrosive properties in primer and/or filler coating compositions by employing certain polyhydroxyl-functional organic compounds, even compounds that occur in nature and are therefore environmentally benign. In particular, the corrosion inhibitors used in the coating materials of the present invention should be effective even in environments with low pH values, without the need for pH changes and without the need for protection from components that form the matrix material of the cured coating. In other words, it should not be necessary to encapsulate the corrosion inhibitors used in the present invention, for example, in mesoporous silica nanocontainers. Moreover, if corrosion occurs without pH changes, the inhibitors thus encapsulated will be ineffective, since they will not be released from the encapsulating material.

The object of the present invention was to overcome the aforementioned drawbacks of the known art and to provide a two-component coating material that can be applied by spray application, in particular as used in automotive repainting, and that tends to provide corrosion protection to different metallic and multi-metallic substrates, in particular substrates containing aluminum, without pretreatment and without the need for encapsulation of the corrosion inhibitor, such as incorporation in mesoporous silica nanocontainers or the like. Furthermore, the corrosion inhibitor employed should already be effective at very low concentrations in the coating material, thus minimizing detrimental effects and changes to the overall properties of the coating material.

（式中、４つの残基Ｒ^１のうちの２つはＯＨであり、他の２つの残基Ｒ^１はＨであり；Ｒ^２＝Ｏ又はＣ＝Ｏであり；そしてＲ^３－Ｒ^４はＣ＝Ｃ又はＨＣ－ＣＨであり；星印＊は下記の式（ＩＩ）における残基Ｒ^５及びＲ^６又は下記の式（ＩＩＩ）における残基ＣＨ－ＣＨ－ＣＨ－ＣＨへの結合部位を表す）、及び式（ＩＩ）の種からなる群から選択される１つ以上の種、

（式中、Ｒ^５は

であり；Ｒ^６＝Ｈ又はＯＨであり、星印＊はＲ^４への結合部位を示し；Ｒ^７及びＲ^８はＨ又はＯＨであり、ただしＲ^７及びＲ^８の少なくとも１つはＨであり；Ｒ^２はＯである）、及び式（ＩＩＩ）の種

（式中、Ｒ^２はＣ＝Ｏである）
を含むマスターバッチ成分、及び
（Ｂ）マスターバッチ成分（Ａ）の１種以上のポリマー及び／又は樹脂の官能基に対して反応性である官能基を含む１種以上の架橋剤を含む硬化剤成分；及び、任意に、
（Ｃ）溶媒成分
を含む溶媒系２液型コーティング組成物を提供することによって解決された。 The problem to be solved by the present invention is as follows:
(A)
a. one or more polymers and/or resins that contain functional groups that are reactive with the functional groups of one or more crosslinkers contained in the hardener component (B);
b. one or more pigments and/or fillers; and c. one or more species containing structural units of formula (I),

wherein two of the four residues R ¹ are OH and the other two residues R ¹ are H; R ² =O or C=O; and R ³ -R ⁴ are C=C or HC-CH; the asterisk * represents the bond site to the residues R ⁵ and R ⁶ in formula (II) below or to the residue CH-CH-CH-CH in formula (III) below, and one or more species selected from the group consisting of species of formula (II),

(Wherein, ^R5 is

R ⁶ =H or OH, with the asterisk * indicating the site of attachment to R ⁴ ; R ⁷ and R ⁸ are H or OH, with the proviso that at least one of R ⁷ and R ⁸ is H; and R ² is O), and a species of formula (III)

(Wherein, ^R2 is C=O)
(B) a hardener component comprising one or more crosslinkers that contain functional groups that are reactive toward the functional groups of the one or more polymers and/or resins of masterbatch component (A); and, optionally,
(C) The problem has been solved by providing a solvent-based two-component coating composition including a solvent component.

The present invention further provides a method for producing the coating composition of the present invention.

The invention further provides a method for coating a metal substrate, in particular an aluminium-containing metal substrate, with a coating composition according to the invention, and the substrate thus coated.

Yet another object of the present invention is a multi-layer coated substrate and a method for producing the same.
A further object of the present invention is the use of one or more species of formula (II) and (III) as defined above in a solvent-based two-component coating composition, in particular to impart corrosion protection properties to the cured coatings formed from the coating composition.

Solvent-Based Two-Part Coating Compositions of the Present Invention The coating compositions of the present invention are preferably in the form of a dispersion or solution, more particularly in the form of a dispersion.

The proportions expressed as % by weight of all components present in the coating composition of the present invention, in other words components (A), (B), optionally (C), and optionally (D) described below, are based on the total weight of the coating composition of the present invention and preferably in each case total 100% by weight.

The coating composition of the present invention is a solvent-based, i.e., solvent-based or non-aqueous coating composition.

The terms "solvent-based", "solvent-based" or "non-aqueous" in connection with the coating composition of the present invention preferably mean a coating composition which comprises as its liquid dilution medium, i.e. as liquid solvent and/or dispersion medium, at least one organic solvent as the main component (with respect to the dilution medium employed). The proportion of organic solvent in the coating composition of the present invention is preferably at least 95.0% by weight or at least 96.0% by weight or at least 97.0% by weight, most preferably at least 99% by weight or at least 99.5% by weight or at least 99.9% by weight, in each case based on the total proportion of the liquid dilution medium present in the coating composition. The liquid dilution medium can be present in the masterbatch component, the hardener component and/or the solvent component or in further constituents or components, if present.

The viscosity of the coating composition of the present invention is preferably suitable for spray application using a spray gun, such as those used in repainting automobiles. Preferably, the viscosity of the coating composition of the present invention, measured using DIN CUP 4 (according to DIN 53211:1987-06) at a temperature of 20°C, is less than 30 seconds, more preferably less than 25 seconds, particularly preferably 15 to 25 seconds, for example 17 to 23 seconds.

The coating composition of the present invention preferably has a non-volatile fraction in the range of 30 to 90% by weight, more preferably in the range of 40 to 80% by weight, very preferably in the range of 45 to 75% by weight, more particularly in the range of 55 to 70% by weight, most preferably in the range of 60 to 65% by weight, in each case based on the total weight of the coating composition.

As used herein, the term "non-volatile fraction" is the calculated total amount of all film-forming components, including all additives, pigments and fillers, as employed in each coating composition. Thus, the non-volatile fraction does not include solvent.

The term "two-part" or "two-component" in relation to coating compositions refers to such coating compositions in which the chemical reaction leading to crosslinking is initiated by mixing two components (masterbatch and hardener) in a ratio predetermined by the manufacturer (DIN 55945: 1996-09) and hardening to form a durable coating. The individual components are not coating materials, since they are not suitable for film formation, are not capable of film formation, or do not form durable coatings. The mixture must be processed within a certain time (pot life or processing time), since after this time the processability or film-forming properties decrease. In two-component spray systems this is generally not a problem, since mixing here takes place only immediately before application in the spray process (Römpp Lexikon, Lacke und Druckfarben, Georg Thieme Verlag 1998; Keyword: "Zweikomponenten-Lacke").

The solvent-based two-component coating composition of the present invention is preferably crosslinkable at temperatures ranging from 18°C to 90°C.

The coating composition of the present invention is preferably a primer coating composition or a filler coating composition, i.e. a coating composition suitable for the production of a primer coating or a filler coating. The terms "primer (coating composition)" (German: "Primer") and "filler (coating composition)" (German: "Füller") are known to the person skilled in the art and are defined, for example, in Römpp Lexikon, Lacke und Druckfarben, Georg Thieme Verlag 1998.

Masterbatch Component (A)
(A)a. Polymer and/or resin containing functional groups The masterbatch component (A) contains one or more polymers and/or resins containing functional groups that are chemically reactive with the functional groups of one or more crosslinkers of the hardener component (B).

One preferred type of polymer and/or resin is a polyhydroxyl-functional polymer and/or resin selected from the group consisting of polyesters, polyethers, polyether polyesters, polyurethanes and poly(meth)acrylates. In such polymers and resins, the functional groups that react chemically with the functional groups of one or more crosslinkers of the hardener component (B) include at least two hydroxyl groups. However, the present invention does not exclude other functional groups, such as primary or secondary amine groups, that react chemically with the functional groups of one or more crosslinkers of the hardener component (B).

For the purposes of the present invention, the expressions "(meth)acryloyl" or "(meth)acrylate" encompass in each case the definitions "methacryloyl" and/or "acryloyl", or "methacrylate" and/or "acrylate". Thus, poly(meth)acrylates can be obtained by polymerizing acrylate monomers, methacrylate monomers or both, optionally including other ethylenically unsaturated monomers.

A second preferred type of polymer and/or resin that is chemically reactive with the functional groups of one or more crosslinkers of the hardener component (B) is one that contains at least two oxirane groups. Such polymers or resins are typically referred to as epoxy resins. However, epoxy groups may be incorporated into the poly(meth)acrylate by using oxirane group-containing ethylenically unsaturated monomers in the polymerization reaction.

Polyhydroxyl-functional polymers and/or resins Polyhydroxyl-functional polymers and/or resins have an average of at least two hydroxyl groups per polymer or resin molecule.

As polyhydroxyl-functional polymers and/or resins it is possible to use all compounds known to those skilled in the art which have an average of at least two hydroxyl groups per molecule and which are oligomeric and/or polymeric. As polyhydroxyl-functional polymers and/or resins it is also possible to use mixtures of different oligomeric and/or polymeric polyols.

Preferably, the polyhydroxyl-functional polymers and/or resins have a weight average molecular weight Mw, measured by means of gel permeation chromatography (GPC) against polystyrene standards, of more than 500 g/mol, in particular from 800 to 100,000 g/mol, more in particular from 1000 to 50,000 g/mol.

Particularly preferred polyhydroxyl-functional polymers and/or resins are selected from the group consisting of polyester polyols, polyurethane polyols, polysiloxane polyols and poly(meth)acrylate polyols.

Preferably, the polyhydroxyl-functional polymers and/or resins have a hydroxyl number of 30-400 mg KOH/g, more preferably 100-300 KOH/g. The hydroxyl number (OH number) indicates the number of mg of potassium hydroxide that corresponds to the amount of acetic acid bound when acetylating 1 g of substance. It is measured by boiling the sample with acetic anhydride-pyridine and titrating the acid formed with potassium hydroxide solution (DIN 53240-2). For pure poly(meth)acrylates, the OH number can also be determined with sufficient accuracy by calculation based on the OH-functional monomers used.

Preferably, the glass transition temperature of the polyhydroxyl functional polymers and/or resins, measured by DSC measurement according to DIN EN ISO 11357-2, is between -150°C and 100°C, more preferably between -120°C and 80°C.

Suitable polyester polyols are described, for example, in EP-A-0 994 117 and EP-A-1 273 640. In one or more embodiments, polyurethane polyols are prepared by reaction of polyester polyol prepolymers with suitable di- or polyisocyanates, as described, for example, in EP-A-1 273 640. Suitable polysiloxane polyols are described, for example, in WO-A-01/09260, the polysiloxane polyols described therein being preferably used in combination with other polyols, more particularly those having a high glass transition temperature.

The most preferred polyhydroxyl-functional polymers and/or resins include one or more poly(meth)acrylate polyols. Polyhydroxyl-functional polymers and/or resins can be employed in conjunction with the poly(meth)acrylate polyol(s), examples of which include polyester polyols, polyurethane polyols, and polysiloxane polyols, especially polyester polyols.

Preferably, the poly(meth)acrylate polyols that can be used are copolymers and have a weight average molecular weight Mw of 1000 to 20,000 g/mol, more particularly 1500 to 10,000 g/mol, measured by means of gel permeation chromatography (GPC) in each case against polystyrene standards.

Preferably, the glass transition temperature of the poly(meth)acrylate polyol copolymer is from -100 to 100°C, more particularly from -60 to less than 20°C (measured by DSC measurement according to DIN-EN-ISO 11357-2).

Preferably, the poly(meth)acrylate polyol copolymer has an OH number of 60 to 300 mg KOH/g, more particularly 70 to 200 KOH/g, and an acid number of 0 to 30 mg KOH/g.

The hydroxyl number (OH number) is determined as described above (DIN 53240-2). The acid number here indicates the number of mg of potassium hydroxide consumed to neutralize 1 g of the compound (DIN EN ISO 2114).

Preferably, hydroxyalkyl (meth)acrylates are used as hydroxyl-functional monomeric components, such as, more particularly, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate.

As further monomeric building blocks of the poly(meth)acrylate polyol copolymers, alkyl(meth)acrylates are used, for example, preferably ethyl(meth)acrylate, propyl(meth)acrylate, isopropyl(meth)acrylate, butyl(meth)acrylate, isobutyl(meth)acrylate, tert-butyl(meth)acrylate, amyl(meth)acrylate, hexyl(meth)acrylate, ethylhexyl(meth)acrylate, 3,3,5-trimethylhexyl(meth)acrylate, stearyl(meth)acrylate or lauryl(meth)acrylate; cycloalkyl(meth)acrylates, for example cyclopentyl(meth)acrylate, isobornyl(meth)acrylate or cyclohexyl(meth)acrylate.

As further monomeric constituents of the poly(meth)acrylate polyol copolymers, it is also possible to use vinyl aromatic hydrocarbons, such as vinyl toluene, alpha-methylstyrene or, in particular, styrene, amides or nitriles of acrylic acid or methacrylic acid, vinyl esters or vinyl ethers, and also, preferably, particularly small amounts of acrylic acid and/or methacrylic acid.

Epoxy resins contain two or more oxirane rings, and can be converted to epoxy resins cured with crosslinkers by reaction of the oxirane rings. Common epoxy resins are prepared by reaction of reactive phenols, alcohols, acids, and amines with epichlorohydrin, and contain oxirane rings in the form of glycidyl groups. There are a virtually infinite number of reactive structures that can be reacted with epichlorohydrin to form epoxy resins, so there are many resins available industrially. In addition, unsaturated aliphatic and alicyclic compounds have been directly epoxidized, for example, with peracetic acid.

For the purposes of the present invention, in principle, all epoxy resins commonly used in formulating solvent-based two-component coating compositions can be used. Epoxy resins which can be used according to the invention are preferably selected from the group consisting of glycidyl ethers, such as bisphenol-A-diglycidyl ether, bisphenol-F-diglycidyl ether, epoxide-novalac, epoxide-o-cresol-novalac, 1,3-propane-, 1,4-butane- or 1,6-hexane-diglycidyl ether and polyalkylene oxide glycidyl ethers; glycidyl esters, such as diglycidyl hexahydrophthalate; glycidyl amines, such as diglycidyl aniline or tetraglycidyl methylene dianiline; cycloaliphatic epoxides, such as 3,4-epoxycyclohexyloxyethane or 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate; and glycidyl isocyanurates, such as trisglycidyl isocyanurate.

(A)b. Pigments and/or Fillers Masterbatch component (A) further comprises one or more pigments and/or fillers.

The term "pigment" is known to the skilled person, for example from DIN 55945 (date: October 2001). "Pigments" in the sense of the present invention preferably refer to powder- or platelet-like compounds that are substantially, preferably completely insoluble in the medium that surrounds them, for example in the coating composition of the present invention. Pigments as defined herein differ from "fillers" at least in their refractive index, the refractive index of pigments being 1.7 or higher.

Suitable pigments are preferably selected from the group consisting of organic and inorganic colour-imparting pigments (including black and white pigments), effect pigments and mixtures thereof.

Examples of suitable inorganic color-imparting pigments include white pigments, such as zinc white, zinc sulfide or lithopone; black pigments, such as carbon black, iron manganese black or spinel black; chromatic pigments, such as chromium oxide, chromium oxide hydrate green, cobalt green or ultramarine green, cobalt blue, ultramarine blue or manganese blue, ultramarine violet or cobalt violet and manganese violet, red iron oxide, cadmium sulfoselenide, molybdate red or ultramarine red; brown iron oxide, mixed brown, spinel phase and corundum phase or chrome orange; or yellow iron oxide, nickel titanium yellow, chrome titanium yellow, cadmium sulfide, cadmium zinc sulfide, chrome yellow or bismuth vanadate. Examples of further inorganic color-imparting pigments are, for example, aluminum oxide, aluminum oxide hydrate, in particular boehmite, titanium dioxide, zirconium oxide, cerium oxide, and mixtures thereof. Examples of suitable organic color-imparting pigments include monoazo pigments, disazo pigments, anthraquinone pigments, benzimidazole pigments, quinacridone pigments, quinophthalone pigments, diketopyrrolopyrrole pigments, dioxazine pigments, indanthrone pigments, isoindoline pigments, isoindolinone pigments, azomethine pigments, thioindigo pigments, metal complex pigments, perinone pigments, perylene pigments, phthalocyanine pigments, or aniline black. Effect pigments include metal effect pigments, but also pearlescent pigments, and the like.

The term "filler" is known to the skilled person, for example from DIN 55945 (date: October 2001). "Filler" in the sense of the present invention preferably refers to a substance that is substantially insoluble, preferably completely insoluble, in the coating composition of the present invention and is used more particularly to increase the volume. "Filler" in the sense of the present invention differs from "pigments" at least in its refractive index, the refractive index of the filler being less than 1.7. Any customary filler known to the skilled person can be used. Examples of suitable fillers include kaolin, dolomite, calcite, chalk, calcium sulfate, barium sulfate, graphite, silicates, such as magnesium silicate, more particularly corresponding phyllosilicates, such as hectorite, bentonite, montmorillonite, talc and/or mica, silica, in particular fumed silica, hydroxides, such as aluminum hydroxide or magnesium hydroxide, or organic fillers, such as textile fibers, cellulose fibers, polyethylene fibers, or polymer powders. For further details, see Römpp Lexikon Lacke und Druckfarben, Georg Thieme Verlag, 1998, p. 250 ff., "Fillers".

The above-mentioned pigments and fillers can be suitably used in the coating composition of the present invention, but pigments containing environmentally problematic elements such as Pb, Cd, Cr, Cu, Mo, Hg, Se, or Zn are less preferred, and it is most preferable that they are not included in the coating composition of the present invention.

Although the pigments and/or fillers as described above may contain silica, it is expressly stated herein that mesoporous silica nanocontainers or silica containing encapsulated species of formulae (II) and (III) are preferably not included in the coating compositions of the present invention. The mere simultaneous presence of silica and any of the species of formulae (II) and (III) should not be confused with the rather elaborate formation of mesoporous silica nanocontainer encapsulated corrosion inhibitors taught by Uleato et al. (see above). As stated above, one object of the present invention was to avoid the need for encapsulation of the corrosion inhibitor, i.e., encapsulation of any of the species of formulae (II) and (III).

The weight ratio of the pigment and/or filler (A)b. to (A)a., i.e., one or more polymers and/or resins containing functional groups reactive to the functional groups of one or more crosslinkers contained in the hardener component (B), is preferably 6:1 to 1:6, more preferably 5:1 to 1:5, even more preferably 5:1 to 1:2 or 5:1 to 1:1, for example 4:1 to 2:1.

（式中、４つの残基Ｒ^１のうちの２つはＯＨであり、他の２つの残基Ｒ^１はＨであり；Ｒ^２＝Ｏ又はＣ＝Ｏであり；そしてＲ^３－Ｒ^４はＣ＝Ｃ又はＨＣ－ＣＨであり；星印＊は下記の式（ＩＩ）における残基Ｒ^５及びＲ^６又は下記の式（ＩＩＩ）における残基ＣＨ－ＣＨ－ＣＨ－ＣＨへの結合部位を表す）、及び式（ＩＩ）の種からなる群から選択される１つ以上の種、

（式中、Ｒ^５は

であり；Ｒ^６＝Ｈ又はＯＨであり、星印＊はＲ^４への結合部位を示し；Ｒ^７及びＲ^８はＨ又はＯＨであり、ただしＲ^７及びＲ^８の少なくとも１つはＨであり；Ｒ^２＝Ｏである）、及び式（ＩＩＩ）の種

（式中、Ｒ^２はＣ＝Ｏである）
をさらに含む。 (A)c. Species containing structural units of formula (I) The master batch composition (A) further comprises one or more species containing structural units of formula (I):

wherein two of the four residues R ¹ are OH and the other two residues R ¹ are H; R ² =O or C=O; and R ³ -R ⁴ are C=C or HC-CH; the asterisk * represents the bond site to the residues R ⁵ and R ⁶ in formula (II) below or to the residue CH-CH-CH-CH in formula (III) below, and one or more species selected from the group consisting of species of formula (II),

(Wherein, ^R5 is

R ⁶ =H or OH, with the asterisk * indicating the site of attachment to R ⁴ ; R ⁷ and R ⁸ are H or OH, with the proviso that at least one of R ⁷ and R ⁸ is H; and R ² =O), and a species of formula (III)

(Wherein, ^R2 is C=O)
Further includes:

The species of formulas (II) and (III) above, and the particularly preferred ones described below, can be incorporated into the coating composition of the present invention to provide a cured coating with corrosion prevention properties.

Among the species represented by formula (II), those selected from the group consisting of flavonols such as quercetin and morin; and flavanones such as naringenin are preferred.

（式中、Ｒ^７及びＲ^８は、上記のように定義され；そして
ａ．Ｒ^６はＯＨであり、Ｒ^３－Ｒ^４はＣ＝Ｃ（フラボノール）であるか；又は
ｂ．Ｒ^６はＨであり、Ｒ^３－Ｒ^４はＨＣ－ＣＨ（フラバノン）である）。 Particularly preferred species of formula (II) are those of formula (IIa)

where R ⁷ and R ⁸ are defined as above; and a. R ⁶ is OH and R ³ -R ⁴ are C═C (a flavonol); or b. R ⁶ is H and R ³ -R ⁴ are HC—CH (a flavanone).

In the most preferred species of formula (IIa), R ³ -R ⁴ are C═C, R ⁶ and R ⁸ are OH and R ⁷ is H (ie, quercetin).

Of the species represented by formula (III), those selected from the group consisting of dihydroxyanthraquinones are preferred. Most preferred are 1,4-dihydroxyanthraquinone and 1,2-dihydroxyanthraquinone (i.e., alizarin).

This species has been employed in coating compositions without being encapsulated or otherwise associated with mesoporous silica nanocontainers as described by Ulaeto et al. Surprisingly, despite the fact that these species of formulae (II) and (III) contain some hydroxy groups and thus are in principle susceptible to reaction with epoxy resins in the same manner as crosslinkers containing free isocyanate groups, coating compositions containing the respective species provide excellent corrosion protection when applied thereon and subsequently cured to metal substrates, particularly aluminum-containing metal substrates.

The total amount of species of formula (II) and/or (III) employed in the coating composition of the present invention is preferably in the range of 1 ppm to 15 wt. %, more preferably 0.1 to 5 wt. %, and most preferably 0.5 to 2.5 wt. %, based on the total weight of the masterbatch component (A). If the amount is below the lower limit, no mitigation of the corrosive effect is detected; if the amount is above the upper limit, film formation may be inhibited or the curing reaction may be poisoned.

Hardener Component (B)
The coating composition, which is a two-part coating composition, comprises at least one crosslinking agent in the hardener component (B), such as: a polyisocyanate crosslinking agent having free isocyanate groups that can react with the hydroxyl and active hydrogen-containing groups (e.g., primary or secondary amino groups) of one or more polymers and/or resins contained in the masterbatch component (A); or a polyamine that can react with, for example, an epoxy resin that may be contained in the masterbatch component (A).

Since it is the nature of the two-part composition that the crosslinking component (B) is stored separately from the masterbatch composition (A) to avoid premature crosslinking, the hardener component (B) does not contain any components that are reactive towards the crosslinker. However, the crosslinking component may contain further inert components, such as a solvent or solvent mixture in which the crosslinker is dissolved or dispersed, or further inert additives as described below.

Crosslinking Agents for Polyhydroxyl-Functional Polymers and/or Resins When the functional groups of at least one polymer and/or resin in masterbatch component (A) are selected from hydroxyl groups, primary and secondary amino groups, it is particularly preferred to use one or more polyisocyanates (as that term is used herein to include diisocyanates) having free isocyanate groups as crosslinking agents.

Examples of suitable polyisocyanate crosslinking agents include, but are not limited to, alkylene polyisocyanates such as hexamethylene diisocyanate, 4- and/or 2,4,4-trimethylhexamethylene diisocyanate, dodecamethylene diisocyanate, 1,4-diisocyanatocyclohexane, 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (isophorone diisocyanate), 2,4'- and/or 4,4'-diisocyanatodicyclohexylmethane, 3-isocyanatomethyl-3,5,5-trimethylcyclohexylisocyanate, aromatic polyisocyanates such as 2,4'- and/or 4,4'-diisocyanatodiphenylmethane, 2,4- and/or 2,6-diisocyanatotoluene, naphthylene diisocyanate, and mixtures of these polyisocyanates. Generally, polyisocyanates having an average of three or more isocyanate groups are used, which may be derivatives or adducts of diisocyanates. Useful polyisocyanates are obtained by reacting an excess of an isocyanate with water, a polyol (e.g., ethylene glycol, propylene glycol, 1,3-butylene glycol, neopentyl glycol, 2,2,4-trimethyl-1,3-pentanediol, hexamethylene glycol, cyclohexanedimethanol, hydrogenated bisphenol A, trimethylolpropane, trimethylolethane, 1,2,6-hexanetriol, glycerin, sorbitol or pentaerythritol), or by reacting an isocyanate with itself to give an isocyanurate. Examples include polyisocyanates containing biuret groups, such as those described in US Pat. Nos. 3,124,605 and 3,201,372 or DE-OS 1,101,394; polyisocyanates containing isocyanurate groups, such as those described in US Pat. No. 3,001,973, DE-PS 1,022,789, 1,222,067 and 1,027,394, and DE-OS 1,929,034 and 2,004,048; polyisocyanates containing urethane groups, such as those described in DE-OS 953,012, BE-PS 752,261 or US Pat. Nos. 3,394,164 and 3,644,457; polyisocyanates containing carbodiimide groups, such as those described in DE-PS Nos. 1,092,007, 3,152,162, and DE-OS 2,504,400, 2,537,685, and 2,552,350; allophanate group-containing polyisocyanates, such as those described in GB-PS 994,890, BE-PS 761,626, and NL-05 7,102,524; and uretdione group-containing polyisocyanates, such as those described in EP-A 0,377,177, each of which is incorporated herein by reference.

Such isocyanate crosslinkers are typically stored separately and combined with the polyhydroxyl functional polymer and/or resin immediately prior to application.

A curing catalyst for the urethane reaction, such as a tin catalyst, can be used in the coating composition. Representative examples are tin and bismuth compounds, including, but not limited to, dibutyltin dilaurate, dibutyltin oxide, and bismuth octoate. If used, the catalyst is typically present in an amount of about 0.05 to 2% by weight tin based on the weight of total solids.

Crosslinking agents for epoxy resins In the following, crosslinking agents which are usually used for the curing of epoxy resins are described, which can be used in the masterbatch component (A) as resins containing functional groups which are reactive towards the functional groups present in the crosslinking agent contained in the hardener component (B). Crosslinking agents of this type are referred to in their function as "epoxide crosslinking agents" according to the relevant literature (for example: Kittel, "Lehrbuch der Lacke und Beschichtungen", Vol. 2, 2nd edition, 1998, pp. 267-318).

Epoxide crosslinkers are compounds with a functionality of 2 or more (compounds with active hydrogen, especially hydrogen bonded to nitrogen or oxygen) whose functional groups can react with oxirane groups. Preferably, the crosslinker is employed substantially stoichiometrically with respect to the epoxy resin. The concentration of oxirane rings in the epoxy resin can be determined, for example, by titration. The amount of crosslinker required can be calculated from the active hydrogen equivalents ("H active equivalents") of the crosslinker.

The crosslinking agents that can be used according to the present invention are preferably those selected from the group consisting of polyamines (including here diamines) and polyamides. Particularly preferred are polyamines. Thus, in its most preferred embodiment, the curing agent may be referred to as an amine-based crosslinking agent.

Particularly preferred polyamines may be selected from the group of aliphatic amines, such as diethylenetriamine, triethylenetetramine or 3,3',5-trimethylhexamethylenediamine; cycloaliphatic amines, such as 1,2-cyclohexyldiamine, isophoronediamine and its isomeric mixtures, or m-xylylenediamine; aromatic amines, such as methylenedianiline or 4,4-diaminodiphenylsulfone; modified amines, such as Mannich bases (e.g. diethylenetriamine-phenol Mannich bases), or amine adducts of 3,3',5-trimethylhexamethylenediamine and bisphenol A diglycidyl ether.

Particularly preferred epoxide crosslinkers of the polyamide type are, for example, polyaminoamides or dicyandiamide.

Solvent component (C)
The coating composition of the present invention comprises as component (C) at least one organic solvent. The concept of "organic solvent" is familiar to the person skilled in the art, for example from the European Directive 1999/13/EC of March 11, 1999.

As component (C) of the coating composition of the present invention, all organic solvents known to those skilled in the art are suitable, as long as the solvent is not reactive with the constituents of the component in which it is used. Most preferred are aprotic organic solvents.

The at least one organic solvent is preferably selected from the group consisting of aliphatic hydrocarbons, aromatic hydrocarbons such as toluene and/or xylene, ketones such as acetone, N-methylpyrrolidone, N-ethylpyrrolidone, methyl isobutyl ketone, isophorone, cyclohexanone, and methyl ethyl ketone, esters such as methoxypropyl acetate, ethyl acetate, butyl glycol acetate, and butyl acetate, amides such as dimethylformamide, and mixtures thereof.

Further Optional Components of the Coating Composition of the Invention The coating composition of the invention may optionally comprise at least one further component, such as a typical additive used in two-component coating compositions.

The at least one further component or additive is preferably selected from the group consisting of antioxidants, antistatic agents, moisture-resistant and dispersing agents, antisettling agents, emulsifiers, flow control aids, solubilizers, defoamers, wetting agents, stabilizers, UV and/or light stabilizers, light protection agents, degassing agents, inhibitors, catalysts, waxes, flexibilizers, flame retardants, hydrophobizing agents, hydrophilizing agents, thixotropic agents, impact modifiers, processing aids, plasticizers, and mixtures of the aforementioned components. The amount of the preferably at least one further component in the coating composition of the invention can vary very widely depending on the intended application. The total amount of such components is preferably 0.01 to 10.0% by weight, more preferably 0.05 to 8.0% by weight, very preferably 0.1 to 6.0% by weight, particularly preferably 0.1 to 5.0% by weight, in each case based on the total weight of the coating composition of the invention.

The additional components may be part of the masterbatch component (A), the hardener component (B) and the solvent component (C) or may alternatively be added in the form of a separate component (D). The additional components are preferably chemically inert to the components of the respective components in which they are utilized.

Methods for Producing Coating Compositions According to the Invention The present invention further provides methods for producing the coating compositions according to the invention.

The method for producing the coating composition of the present invention preferably comprises the steps of:
i. First, (A)a. one or more polymers and/or resins containing functional groups reactive to the functional groups of one or more crosslinkers contained in the hardener component (B) are mixed with at least a portion of (A)b. one or more pigments and/or fillers, wherein (A)a. one or more polymers and/or resins containing functional groups reactive to the functional groups of one or more crosslinkers contained in the hardener component (B) are optionally and preferably pre-dissolved and/or pre-dispersed in at least a portion of the organic solvent contained in the final coating composition;
ii. adding the remaining A(b). one or more pigments and/or fillers (if not fully added in step i.) while mixing, and adding, while mixing, one or more species of formula (II) and/or (III) as defined above;
iii. milling the mixture thus obtained, preferably using a bead mill, until the Hegman fineness is determined to be preferably less than 25 μm, more preferably less than 23 μm, and most preferably less than 20 μm, and iv. adding hardener component (B), optionally solvent component (C) and optionally component (D) under mixing conditions to achieve a homogenous coating composition, preferably maintaining the temperature during all mixing steps at a temperature below 50° C.

Step iv. is preferably carried out with a spray gun, such as those used for repainting automobiles.

Method of Coating a Substrate with a Coating Composition According to the Invention The present invention further provides a method of coating a metal substrate with a coating composition according to the invention, wherein the method comprises at least step (i) of contacting the metal substrate with a coating composition according to the invention.

The term "contacting" in the sense of the present invention preferably refers to spraying the coating composition of the present invention onto a substrate to form a coating layer on the substrate.

Such spraying is preferably carried out by electrostatic spraying, air spray coating or airless spray coating. The resulting coating film has a dry thickness, when dried at 23°C for 60 minutes, preferably in the range of 25 to 100 μm, more preferably 30 to 90 μm, and most preferably 40 to 80 μm. The coating film may be cured by heating at a temperature preferably in the range of 18 to 90°C, more preferably 30 to 80°C, and most preferably 50 to 70°C for 5 to 120 minutes.

However, if the thus coated substrate, preferably at least partially dried, is further coated with a subsequent coating composition, such as a topcoat coating composition or a clearcoat coating composition, and fully cured together with such subsequently applied coating layer, the curing step to full curing of the coating layer can be omitted, at least in part. This possibility of a wet-on-wet coating method is explained further below when describing a method for coating a substrate with a multi-layer coating.

Metallic Substrates The substrates used according to the invention are preferably selected from the group consisting of iron, steel, aluminum or alloys thereof, more preferably aluminum-based alloys, which alloys can optionally comprise at least one further metal and/or metalloid, for example copper. Preferably, the substrates here each have at least one surface of iron, steel, aluminum or alloys thereof, more preferably they are entirely composed of iron, steel, aluminum or alloys thereof. Suitable steels are preferably steels selected from the group consisting of cold-rolled steel, hot-rolled steel, high-strength steel, galvanized steel, for example dipping galvanized steel, alloy galvanized steel (for example Galvalume®, Galvannealed® or Galfan®), and aluminized steel. Examples of suitable alloys include alloys of aluminum and copper. Particularly preferred are substrates made of aluminum or aluminum-containing alloys.

The substrates used here may in particular be metal bodies of automobiles and commercial vehicles, but also of aircraft, ships, etc.

Before being coated with the coating composition of the invention, the metal substrates used according to the method for coating substrates according to the invention may be pretreated with a suitable, preferably aqueous, pretreatment composition. Such pretreatment compositions are known to the person skilled in the art and are commercially available. For example, substrates based on aluminum, aluminum or aluminum-containing alloys may be pretreated by tartaric-sulfuric anodizing (TSA) according to DIN EN 4704 (date: May 2012). Steel substrates or steel-based substrates may be pretreated, for example, by pretreatment according to DIN EN ISO 12944-4 (date: July 1998). The grade of the steel substrates or steel-based substrates used is preferably at least 2.5. The grade of the steel may be determined according to DIN EN ISO 8501-1 (date: December 2007).

All preferred embodiments described herein in relation to the coating composition of the present invention are also preferred embodiments of the coating composition of the present invention to be used in the method of the present invention for coating a substrate.

The present invention further relates to a method for coating a substrate with a multi-layer coating, comprising at least the following steps:
There is provided a method for coating a substrate with a multi-layer coating, comprising the steps of: (i) contacting a metal substrate with the coating composition of the present invention for application of the coating composition to the substrate, particularly preferably by spray coating; and (ii) applying a further coating composition, preferably a topcoat coating composition or a clearcoat coating composition, to the coating layer formed by applying the coating composition in step (i), preferably by spray coating.

All preferred embodiments described herein in relation to the coating composition of the invention are also preferred embodiments of the coating composition of the invention used in the method of the invention for coating a substrate with a multi-layer coating. The same applies to metal substrates for which the method for coating a substrate with a primer and/or filler coat is described.

A further coating composition, more particularly a topcoat coating composition or a clearcoat coating composition, most preferably a topcoat coating composition, is usually applied to the coating layer formed in step (i). The coating layer formed in step (i) is preferably dried prior to application of the further coating composition according to step (ii). The term "drying" in the context of the present invention preferably refers to removing at least a portion of the solvent from the applied coating material. Drying may first be performed at 15-30°C for 10-120 minutes. Although some curing may occur during drying, it is preferred that the layer formed in step (i) does not cure, or at least does not cure completely (wet-on-wet method).

The general techniques for application of the further coating composition according to step (ii) are similar to those described above for the coating layer formed from the coating composition according to the invention. The further coating composition, e.g. the topcoat coating composition, is applied at a conventional and known film thickness, e.g. a dry film thickness after curing in the range of 15 to 100 μm, more particularly 40 to 80 μm or 50 to 75 μm.

Curing is carried out according to conventional and known techniques, for example by heating in a forced air oven or by irradiation with infrared lamps. In the case of radiation curing systems, photocuring by UV irradiation is also possible. Curing may be carried out, for example, at elevated temperatures in the range of about 15° C. to 90° C., preferably at 40-80° C., for example 50-70° C. The duration of the curing step is likewise individually selected. For example, curing may be carried out for a period of 5 to 120 minutes, preferably 15 to 45 minutes. Curing can also be optionally preceded by a flashing or pre-drying step, for example for a period of 1 to 60 minutes, preferably at room temperature (i.e. 23° C. in the context of the present invention). After step (ii) has been carried out, it is particularly preferred to dry or cure for a period of 15 minutes to 2 hours, preferably at 40-80° C., more preferably 50-70° C.

Further provided by the present invention is a multi-layer coating obtained by the method of the present invention.

The present invention further provides a metal substrate coated with the coating composition of the present invention. The present invention further provides a component or article manufactured from at least one substrate so coated. Suitable substrates for use in this method are the same as those described herein above.

Method of using species according to formulae (II) and (III) to provide corrosion protection The present application also relates to the use of one or more species of formulae (II) and (III) as defined above in solvent-based two-part coating compositions, in particular to provide corrosion protection to cured coatings formed from the coating compositions.

All of the preferred species embodiments according to formulae (II) and (III) and all of the embodiments relating to the solvent-based two-part coating compositions described herein in relation to the coating compositions of the present invention are also preferred embodiments of the method of use of the present invention.

The present invention will now be explained in more detail with reference to experimental data.

Test Acid Salt Spray Test (AASS)
The Acid Salt Spray Mist Test (AASS) is used to determine the corrosion resistance of coatings on substrates. According to DIN EN ISO 9227 (date: June 2017), the Acid Salt Spray Mist Test was carried out on a coated conductive substrate, namely aluminum. Here, the investigated samples were in a chamber where they were continuously sprayed with a 5% common salt solution with a controlled pH ranging from 3.1 to 3.3 at a temperature of 35°C for a duration of 1008 hours. This spray deposited on the investigated samples and covered them with a corrosive film of salt water.

Since the substrate corrodes along the score lines during the DIN EN ISO 9227 AASS salt spray test, the coating on the samples to be investigated was cut down to the substrate with a knife before the acid salt spray test according to DIN EN ISO 9227 AASS in order to be able to investigate the level of undermining according to DIN EN ISO 4628-8 (date: 01.03.2013). As a result of the corrosion process, the coating is more or less damaged during the test. The degree of undermining (in mm) is an indicator of the corrosion resistance of the coating. Note that the average undermining level stated in the results below is the average of the individual values evaluated for 3 to 5 panels, and the individual value for a panel is the average of the undermining level at 11 measurement points on the panel.

Gloss, blistering, adhesion Gloss and adhesion were determined before and after a constant weather test with an exposure time of 240 hours. After the constant weather test, the formation of blisters was also evaluated. The constant weather test was carried out according to EN ISO 6270-2 (April 2018) with an exposure time of 240 hours.

The gloss was evaluated at an angle of 60° on 10 different spots on one coated specimen before and after a constant weather test according to DIN EN 13523-2 (August 2014). The average value with one-digit accuracy is reported in the results.

The blister grade was assessed according to DIN EN ISO 4628-2 (July 2016) depending on the density of the blisters and their size. The assessment was carried out directly after the constant climate test and subsequent relaxation periods of 1 hour and 24 hours at ambient conditions (22°C, 50% r.h.).

Adhesion was evaluated by cross-cut test according to ISO 2409. A multi-blade cutting tool was used to create a cross-hatch pattern from the coating to the substrate. The delaminated parts of the coating were removed by brushing with a soft brush. Then adhesive tape was applied over the cross-hatch to remove all delaminated parts of the coating. Classification was according to table 1 of ISO 2409. Cross-hatch tests were performed before and after the constant climate test. After the climate-controlled test, cross-hatch tests were performed after 1 hour and 24 hour recovery times. During the climate-controlled test, the cross-hatch was covered with adhesive tape to avoid corrosion of the prepared cross-hatch.

Filler Coating Compositions Solvent-Based Two-Part Hydroxyl/Isocyanate Filler Coating Compositions Table 1 lists the components (parts by weight) of the comparative filler coating compositions C1 and C2, and the inventive filler coating compositions E1-E4. The masterbatch composition (A) ("A pack") contains a hydroxyl group-containing polymer (polyacrylate polyol), pigments and fillers ( _TiO2 and _BaSO4 ), solvents (xylene and butyl acetate), and 0.50 or 1.00 parts by weight of corrosion inhibitors (I1, I3 and I4) for the inventive examples, and 1 part by weight of 3-methylanthraquinone (I2) for the comparative composition C2. The hardener component (B) ("B pack") contains an isocyanate group-containing aliphatic hardener and a solvent mixture.

Positions 1-7 and 10 in Table 1 are parts by weight as 100% solids. However, the polyacrylate polyol in position 1 was used pre-dispersed in butyl acetate/xylene (3:1; w/w) as a dispersion with 65% solids by weight. The solvent content of this dispersion was assigned to positions 8 and 9, and only the solids of this dispersion was assigned to position 1. Additionally, the isocyanate hardener in position 10 was used pre-dissolved in the solvent mixture in position 11.

To prepare inventive filler coating compositions E1-E4 containing different corrosion inhibitors I1, I3 and I4 and comparative filler coating composition C2 (containing material I2), the amounts of positions 1, 2, 3, 8 and 9 used in comparative filler coating composition C1 were reduced to maintain the same pigment to polyacrylate polyol weight ratio of 74:26 in masterbatch component (A) and solvent content of about 21% by weight of masterbatch component (A) for all filler coating compositions. The amount of isocyanate curing agent in hardener component (B) was selected to provide a molar ratio of OH groups (from polyacrylate polyol) to NCO groups (from isocyanate curing agent) of 1:1.08.

For all filler coating compositions, positions 1 and 2 were fed into a mixing vessel and positions 3-9 were added while mixing at about 1000-1500 rpm. The resulting mixture was then mixed for a further 30 minutes at about 1500 rpm using a dissolver (VMA Getzmann, Dispermat CN20) while maintaining a temperature below 50°C (C1: about 47°C; E1-E5: about 36°C). For composition C1, the determined Hegman fineness was about 23 μm (DIN EN ISO 1524, June 2013). The inventive filler coating compositions E1-E4 and the comparative filler coating composition C2 were further milled in a bead mill (0.5 L grinding vessel; 200 g Siliquarzit® pearls 1.8-2.2 mm per 400 g masterbatch component (A)) at about 2000-2100 rpm with maximum cooling for various times (C2: 45 min; E1: 90 min; E2: 300 min; E3: 50 min; and E4: 60 min) to obtain a Hegman fineness of less than about 23 μm (C2: 23 μm; E1: 20 μm; E2: 20 μm; E3: <23 μm; and E4: <23 μm).

To obtain the final filler coating compositions C1, C2 and E1-E4 for application to aluminum alloy panels, the masterbatch component (A) and the hardener component (B) were thoroughly mixed and diluted with solvent composition S (1-methoxypropyl acetate, 2-butyl acetate and xylol; in C1: 0% by weight; in C2, E1-E4: about 10% by weight) to a DIN Cup 4 spray application viscosity at 20°C of about 19 seconds to about 22 seconds.

¹ polyacrylate polyol (solid; OH number: 149 mg KOH/g, hydroxyl equivalent: 378),
^2. 1,4-Dihydroxyanthraquinone
³ 3-Methylanthraquinone (not of the present invention)
^4. Alizarin (1,2-dihydroxyanthraquinone)
⁵ Quercetin 6 Mixture of aliphatic polyisocyanate oligomers based on IPDI and HDI
^7. Mixture of the following solvents used to dilute position 10:

Solvent-Based, Two-Part Epoxy/Amine Filler Coating Compositions Table 2 lists the components (parts by weight) of the comparative filler coating compositions C3 and C4, and the inventive filler coating compositions E5-E8. The masterbatch composition (A) ("A pack") contains the epoxy resin, wetting and dispersing additive, pigments ( _TiO2 , _BaSO4 , and platelet talc), and solvents (xylene, methoxypropanol, isobutanol), with 0.50 or 1.00 parts by weight of the corrosion inhibitors (I1, I3, and I5) for the inventive examples. The hardener component (B) ("B pack") contains an amine group-containing hardener mixture and a solvent mixture.

Positions 1-9 and 17 in Table 2 are parts by weight as 100% solids. However, the epoxy resin mixture in position 1 was pre-dispersed in the solvent in positions 10 and 11, and a wetting dispersant was pre-dissolved in positions 12 and 13. Additionally, the amine hardener mixture in position 17 was pre-dissolved in the solvent mixture in position 18.

To prepare inventive filler coating compositions E5-E8 and comparative filler coating composition C4 containing different corrosion inhibitors I1, I3, and I4 and non-inventive compound I2, the amounts of positions 1-5, 14, and 15 used in the comparative filler coating compositions were reduced to maintain the same pigment to epoxy resin weight ratio of 70:30 and solvent content of about 24 wt% in masterbatch component A for all filler coating compositions. The amount of amine hardener mixture in hardener component (B) was selected to provide a molar ratio of epoxy groups (from the epoxy resin mixture) to amine groups (from the amine hardener mixture) of 100:16.45.

For all filler coating compositions, positions 1, 10 and 11 were fed into a mixing vessel and position 2 (premixed with positions 12 and 13) was added. This mixture was mixed for 10 minutes at 1500 rpm using a dissolver (VMA Getzmann, Dispermat CN20), followed by the addition of 15, 4, 5 and 14 in that order, then positions 6-9, and finally 3. The resulting mixture was then mixed for an additional 30 minutes at approximately 1500 rpm while maintaining a temperature of 33-36°C. The filler coating compositions were further milled in a bead mill (0.5 L grinding vessel; 202 g Siliquarzit® pearls 1.8-2.2 mm per 400 g masterbatch component A) at about 2000 rpm under cooling for various times (C3: 70 min; C4: 70 min; E5: 60 min; E6: 60 min; E7: 70 min; and E8: 90 min) to obtain Hegman finenesses of less than about 23 μm (after 4:1 dilution with butyl glycol acetate) (C3: 10 μm; C4: 20 μm; E5: <20 μm; E6: 20 μm; E7: 20 μm; and E8: 23 μm), where the Hegman finenesses were determined as described above.

To obtain the final filler coating compositions C3, C4 and E5-E8 to be applied to the aluminum alloy panels, the masterbatch A and the hardener composition B were thoroughly mixed and diluted with the solvent composition S (1-methoxypropyl acetate, 2-butyl acetate and xylol; in C3: about 5% by weight; in C4, E5, E7 and E8: about 15% by weight; and in E6: about 13% by weight) to a DIN Cup 4 spray application viscosity at 20°C of about 19 seconds to about 22 seconds.

⁷ Epoxy resin mixture (84% by weight of epoxy resin A: epoxy group content: 3800-4250 mmol/kg; 16% by weight of epoxy resin B: Beckopox EM 460 (solvent-free))
^8. 1,4-Dihydroxyanthraquinone
⁹ 3-Methylanthraquinone (not of the present invention)
¹⁰ Alizarin
^11. Quercetin
Used to disperse ^12- position 1 epoxy resin mixtures
¹³ Used to dissolve the wetting and dispersing agent at position 2,
¹⁴ Proprietary mixture of oligomeric and polymeric amines (amine value: approx. 270±20 mg KOH/g)
A proprietary solvent mixture used to dissolve the amine hardener mixture at ¹⁵ position 16.

Application of the coating compositions Application of a two-part hydroxyl/isocyanate system and overcoating with a topcoat Filler coating compositions E1-E4 of the invention and comparative filler coating compositions C1 and C2 were applied by spraying (spray gun: SATA3000RP, nozzle 1.3 mm, pressure 2.5 bar) onto aluminum alloy panels (AA6014 for AASS tests, AlMgMn4.5 for other tests). After application, the resulting films were dried at room temperature (23° C.) for 60 minutes (dry film thickness of filler coating: 58±9 μm, except for coating composition E3: 39 μm).

The filler-coated film thus obtained was overcoated by spray application (spray gun: SATA 3000 RP, nozzle: 1.4 mm, pressure: 2.5 bar) with a white topcoat (masterbatch: Series 68 CV, product number: 68-RAL 9010; hardener: Hardener CV, product number: 922-138; thinner: product number: 352-216; 4:1:1 (v/v/v); all available from BASF Coatings GmbH) and dried at 60°C for 30 minutes to obtain a dry film thickness of 66 μm.

Application of the two-part epoxy/amine system and overcoating with a topcoat Filler coating compositions E5 to E8 according to the invention and comparative filler coating compositions C3 and C4 were applied by spraying (spray gun: SATA 100BF RP, nozzle: 1.6 mm, pressure: 2.5 bar). After application, the films obtained were dried at room temperature (23° C.) for 60 minutes (dry film thickness of the filler coating: 52±6 μm, except for coating composition C2: 71 μm).

The filler-coated film thus obtained was overcoated by spray application (spray gun: SATA 3000 RP, nozzle: 1.4 mm, pressure: 2.5 bar) with a white topcoat (masterbatch: Series 68 CV, product number: 68-RAL 9010; hardener: Hardener CV, product number: 922-138; thinner: product number: 352-216; 4:1:1 (v/v/v); all available from BASF Coatings GmbH) and dried at 60°C for 30 minutes to obtain a dry film thickness of 58 μm.

Corrosion test results

As shown in Table 3, in the AASS tests, filler coating compositions E1-E4 of the present invention were significantly superior to comparative filler coating composition C1, which did not contain a corrosion inhibitor, and comparative filler coating composition C2, which was 3-methylanthraquinone without hydroxyl groups. Coating composition E3 also still showed good corrosion inhibition, despite the reduced dry film thickness of this example compared to the other examples.

Furthermore, the results of the cross-cut test, gloss (60°) test and determination of the number/size of blisters on aluminum alloy panels (AlMgMn4.5) subjected to a constant climate test (CCT; 240 hours) were very satisfactory, with no adverse effect of the corrosion inhibitors observed in any of the test parameters.

As shown in Table 4, in the AASS tests, filler coating compositions E5-E8 of the present invention were significantly superior to comparative filler coating composition C3, which did not contain a corrosion inhibitor, even though comparative filler coating composition C3 was applied at a high dry film thickness. Comparative filler coating composition C4, which is 3-methylanthraquinone without hydroxyl groups, was found to be significantly less effective than the corrosion inhibitors used in filler coating compositions E5-E8 of the present invention.

Claims (17)

(A)
a. one or more polymers and/or resins that contain functional groups that are reactive with the functional groups of one or more crosslinkers contained in the hardener component (B);
b. one or more pigments and/or fillers; and c. one or more species containing structural units of formula (I),

wherein two of the four residues R ¹ are OH and the other two residues R ¹ are H; R ² =O or C=O; and R ³ -R ⁴ are C=C or HC-CH; the asterisk * represents the bond site to the residues R ⁵ and R ⁶ in formula (II) below or to the residue CH-CH-CH-CH in formula (III) below, and one or more species selected from the group consisting of species of formula (II),

(Wherein, ^R5 is

R ⁶ =H or OH, with the asterisk * indicating the site of attachment to R ⁴ ; R ² =O; R ⁷ and R ⁸ are H or OH, with the proviso that at least one of R ⁷ and R ⁸ is H), and/or a species of formula (III):

(Wherein, ^R2 is C=O)
(B) a hardener composition comprising one or more crosslinkers that comprise functional groups that are reactive towards functional groups of said one or more polymers and/or resins; and, optionally,
(C) A solvent-based two-part coating composition comprising a diluent composition. The species of formula (II) is a species of formula (IIa)

wherein R ⁷ and R ⁸ are defined in claim 1; and
2. The solvent-based two-part coating composition of claim 1, wherein: a. R ⁶ is OH and R ³ -R ⁴ are C═C; or b. R ⁶ is H and R ³ -R ⁴ are HC—CH. The solvent-based two-part coating composition of claim 1, wherein the species of formula (II) is selected from the group consisting of quercetin, morin and naringenin, and/or the species of formula (III) is selected from 1,2-dihydroxyanthraquinone and 1,4-dihydroxyanthraquinone. The solvent-based two-component coating composition according to any one of claims 1 to 3, wherein the species containing the structural unit of formula (I) is quercetin. The solvent-based two-component coating composition according to any one of claims 1 to 4, wherein the one or more polymers and/or resins containing functional groups reactive to the functional groups of the one or more crosslinkers contained in the hardener component (B) are polyhydroxy-functional polymers and/or resins, the one or more crosslinkers are polyisocyanates having free isocyanate groups, or the one or more polymers and/or resins containing functional groups reactive to the functional groups of the one or more crosslinkers contained in the hardener component (B) are epoxy resins, and the one or more crosslinkers are selected from the group consisting of polyamines and polyamidines. The solvent-based two-component coating composition according to any one of claims 1 to 5, wherein the mass ratio of (A)b. the sum of the pigment and filler to (A)a. the one or more polymers and/or resins containing functional groups reactive to the functional groups of the one or more crosslinking agents contained in the hardener component (B) is 1:5 to 5:1. The solvent-based two-component coating composition according to any one of claims 1 to 6, which is a primer coating composition or a filler composition or both. A solvent-based two-component coating composition according to any one of claims 1 to 7, having a DIN Cup 4 viscosity (DIN 53211:1987-06) of less than 30 seconds. The solvent-based two-component coating composition according to any one of claims 1 to 8, wherein the masterbatch composition (A) contains, in total, 1 ppm to 15 wt. % of one or more species of formula (II) and/or (III), based on the total weight of the masterbatch composition (A). i. first, (A)a. one or more polymers and/or resins containing functional groups reactive to functional groups of one or more crosslinkers contained in the hardener component (B) are mixed with at least a portion of (A)b. one or more pigments and/or fillers, wherein (A)a. one or more polymers and/or resins containing functional groups reactive to functional groups of one or more crosslinkers contained in the hardener component (B) are optionally and preferably pre-dissolved and/or pre-dispersed in at least a portion of the organic solvent contained in the final coating composition;
ii. adding, while mixing, the remaining A(b). one or more pigments and/or fillers if not fully added in step i., and adding, while mixing, one or more species of formula (II) and/or (III) as defined in any one of claims 1 to 9;
iii. milling the mixture thus obtained, preferably using a bead mill, until the Hegman fineness is determined to be preferably less than 25 μm, more preferably less than 23 μm, and most preferably less than 20 μm, and iv. adding a hardener component (B) and optionally a solvent component (C) under mixing conditions to achieve a homogenous coating composition. A method for coating a metal substrate with the coating composition according to any one of claims 1 to 9, comprising at least step (i) of contacting the metal substrate with the coating composition of the present invention. A method of coating a metal substrate with the coating composition of claim 11, wherein the metal substrate is aluminum or contains aluminum. A coated metal substrate obtained by the method according to claim 11 or 12. At least the following steps:
10. A method for coating a substrate with a multi-layer coating, comprising the steps of: (i) contacting a metal substrate with a coating composition according to any one of claims 1 to 9 for application of the coating composition to the substrate, in particular preferably by spray coating; and (ii) applying a further coating composition, preferably a topcoat coating composition or a clearcoat coating composition, to the coating layer formed by applying the coating composition in step (i), preferably by spray coating. The method for coating a substrate with a multilayer coating according to claim 14, wherein the metal substrate is aluminum or contains aluminum. A multilayer coated metal substrate obtained by the method according to claim 14 or 15. To provide corrosion protection to a cured coating formed from the coating composition,
A method of using one or more species of formula (II) and (III) as defined in any one of claims 1 to 9 in a solvent-based two-component coating composition comprising: (A) a masterbatch composition comprising (A)a. and (A)b. as defined in any one of claims 1 to 9; and (B) a hardener composition as defined in any one of claims 1 to 9, and optionally (C) a diluent composition.